1. Field of the Invention
This application relates to methods and apparatus for providing services to subscribers in a telecommunications network. In particular, but not exclusively, this application relates to the delivery of telephone calls to subscribers having multiple telephony devices.
2. Description of the Related Technology
Telephone subscribers have long had to deal with a proliferation of telephony devices through which calling parties may contact them. For example, a business user might have a fixed-line telephone for use in the office and a mobile telephone for use at other locations. Each telephony device has associated advantages; whilst a mobile telephone provides the user with mobility, a fixed-line telephone typically provides less costly call services, no need to recharge a battery, and also better service in areas where there is poor signal strength such as inside a building.
To avoid confusing calling parties with telephone dialing numbers for each of the telephony devices of a subscriber, a one-telephone dialing number telephony service allows a subscriber to publish a single telephone dialing number on which they can be contacted. Preferably, when the single telephone dialing number is called, all of the subscriber's telephony devices will typically ring, preferably simultaneously. The subscriber is thus able to answer the call at the telephony device of his choosing.
Prior art attempts to provide one-telephone dialing number telephony services typically require each physical telephony device to be assigned a unique telephone number, so are not true one-telephone dialing number services. When a subscriber's published telephone dialing number is called, the terminating telephony system providing the one-telephone dialing number service will ring each device by establishing separate call legs using each device's telephone dialing number. One disadvantage of such an approach is that since each physical telephony device has a separate telephone dialing number, calls originating from each of the devices will generally display each respective device's number as a calling line identifier (CLI). Such disclosure of each device's CLI is generally undesirable, for example it may cause confusion by presenting un-published telephone dialing numbers for the subscriber. Another disadvantage of such an approach is that additional telephone dialing numbers are required to offer the service which causes additional management overhead for the service provider and uses up more telephone dialing numbers from a limited pool of publicly available telephone dialing numbers.
Other prior art attempts to provide one-telephone dialing number telephony services can be found where the telephony devices are Session Initiation Protocol (SIP) compliant. Each SIP-compliant telephony device registers contact information, such as IP address, against a common ‘address of record’ which typically maps to the subscriber's telephone number. When the subscriber's number is called, the terminating telephony system sends (or ‘forks’) the call to each telephony device using standard procedures found in SIP. Whilst this approach avoids the need to assign each device its own telephone dialing number, it has the disadvantage that all telephony devices must support SIP (or that a protocol conversion unit is deployed which gives the appearance that a telephony device supports SIP).
It would therefore be desirable to provide a one-telephone dialing number telephony service where only a single telephone dialing number is required for each subscriber, despite each subscriber having multiple telephony devices on which they wish to be called.